1. Field of the Invention
The present invention relates to a scroll type fluid apparatus adapted for use in fluid machines such as, for example, air compressors, vacuum pumps and so on. The invention particularly relates to a semi-lubricated scroll-type fluid apparatus in which a lubricant is not supplied between the scroll wrap of the orbiting scroll member and the scroll wrap of the stationary scroll member.
2. Prior Art
Generally, a semi-lubricated scroll-type fluid apparatus comprises a casing, a drive shaft journalled on the casing and provided with a crank shaft portion formed at the inner end thereof which is located within the casing, an orbiting scroll member rotatably journalled on the crank shaft portion of the drive shaft through a bearing and including a mirror-finished plate and an orbiting scroll wrap extending upright on the plate, a stationary scroll member mounted on the casing and including an annular flange having an annular recess therein, a mirror-finished plate, and a stationary scroll wrap extending upright on the plate and formed so as to cooperate with the orbiting scroll wrap to define a sealed space therebetween, a suction port for fluid formed through the casing or through the annular flange of the stationary scroll member, the suction port communicating with the annular recess of the annular flange, a discharge port for fluid formed through the mirror-finished plate of the stationary scroll member, and a sealing member disposed in the annular space of the annular flange of the stationary scroll member for sealing the space in the recess communicating with the suction port from the interior of the casing.
When the scroll type fluid apparatus mentioned above functions as an air compressor, the drive shaft is driven by means of a motor located outside the housing so as to drive the orbiting scroll member. Air sucked through the suction port is compressed in the sealed space or compression chamber defined between the stationary and orbiting scroll wraps, and then the compressed air is discharged through the discharge port into an air tank located outside.
In the conventional scroll type fluid machine mentioned above, lubricant, which is received within the casing and is adapted to be spread over the orbiting scroll member and bearings to lubricate and/or cool them, is reliably prevented from leaking out to the suction port side, since the sealing member is disposed in the annular recess of the annular flange to seal the space communicating with the suction port from the interior of the casing.
However, the conventional scroll type fluid machine mentioned above suffers from the following disadvantages.
First, the stationary scroll member tends to be large in order to accommodate the sealing member.
Second, the fact that the annular flange and the mirror-finished plate of the stationary scroll member are formed integrally with each other results in a difficult manufacturing process which leads not only to an increase in manufacturing costs but also to a debasement in accuracy of the stationary scroll wrap, thereby substantially lowering the compression efficiency, reliability and durability of the machine.